NickC
Well-known member
ok everything seems to "work" except the general output volume is really too low, I know it's a mess but maybe someone can see something I don't see, thanks in advance
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Breadboarding Tone VEndor mk2 troubleshoot
- Thread starter NickC
- Start date
BuddytheReow
Breadboard Baker
Not sure what this resistor is supposed to do. It's just sitting in the power rails and won't do anything for the overall circuit since the power will just bypass it. If this R3 per the schematic then you'll have to adjust your layout.
Big Monk
Well-known member
This. Your Q3 voltage divider string is jacked up.
The output cap should be tied to the junctions of the 2 resistors, not to power.
This is what yours looks like right now:
It should look like this:
Big Monk
Well-known member
The question we have to ask is naturally: Do you know why the output was reduced?
BuddytheReow
Breadboard Baker
I would like to know for my own benefit. Tone Benders are your specialty
Big Monk
Well-known member
Keep in mind, it's not Tonebender MK II specific.
This is the same exact split-load collector resistor/voltage divider circuit as the Fuzz Face.
Big Monk
Well-known member
Suspense is not really my jam.... 
The Rc3a/Rc3b network in the MK II (Rc2a/Rc2b in a FF) is a fixed voltage divider.
We all know the effects of moving a transistor stages bias point toward the power rail and to ground. Gating occurs initially and then silence happens for voltages at the power rail and glitching/velcro initially and then silence toward ground.
EDIT (Thanks Dave!): For the nominal 470/8.2k string with a 9 vDC source, not much of the signal of the total signal is let across the 470.
If you have experimented with the nominal 470 ohm RcXa value, you'll know from experience that as you increase that value, the output volume increases.
Since @NickC was essentially bypassing RcXa, the output volume would have been super low (Jumper = 0 ohm RcXa).
The Rc3a/Rc3b network in the MK II (Rc2a/Rc2b in a FF) is a fixed voltage divider.
We all know the effects of moving a transistor stages bias point toward the power rail and to ground. Gating occurs initially and then silence happens for voltages at the power rail and glitching/velcro initially and then silence toward ground.
EDIT (Thanks Dave!): For the nominal 470/8.2k string with a 9 vDC source, not much of the signal of the total signal is let across the 470.
If you have experimented with the nominal 470 ohm RcXa value, you'll know from experience that as you increase that value, the output volume increases.
Since @NickC was essentially bypassing RcXa, the output volume would have been super low (Jumper = 0 ohm RcXa).
Last edited:
BuddytheReow
Breadboard Baker
Is there a limit to how big the 470 resistor can be? Could I throw in, say, 1k or 4.7k?Suspense is not really my jam....
The Rc3a/Rc3b network in the MK II (Rc2a/Rc2b in a FF) is a fixed voltage divider.
We all know the effects of moving a transistor stages bias point toward the power rail and to ground. Gating occurs initially and then silence happens for voltages at the power rail and glitching/velcro initially and then silence toward ground.
For the nominal 470/8.2k string with a 9 vDC source, not much of the signal is attenuate across the 470.
If you have experimented with the nominal 470 ohm RcXa value, you'll know from experience that as you increase that value, the output volume increases.
Since @NickC was essentially bypassing RcXa, the output volume would have been super low (Jumper = 0 ohm RcXa).
Big Monk
Well-known member
It's interactive with the volume control. So increasing the nominal 470 ohm shifts the upper end of available volume when the Volume control is increased.
The split-load/voltage divider network is there so you don't absolutely pummel the input of whatever the fuzz is hitting.
Larger values will make unity volume lower on the volume dial and provide more output signal with the volume all the way up. 1.2k is probably the upper useful limit.
For the record, 470 ohm typically provides a fair amount of volume boost when the transistors are biased properly.
Chuck D. Bones
Circuit Wizard
Incorrect. Most of the signal is attenuated.
For a 8.2K / 470Ω voltage divider, the loss is 25dB. Changing the ratio of those resistors affects the volume. Changing the sum of those resistors affects the bias.
Yes, of course there is a limit to how large either resistor can be. If you go too large, then the last transistor will saturate and you get either gating or no signal. You can make the 470Ω resistor larger for more volume. Keep in mind that you are affecting both the bias & volume when you change that resistor. If you want to change only the volume and keep the bias constant, then you need to change both resistors, keeping the sum constant.
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Big Monk
Well-known member
Definitely not what I meant! I corrected it and the other grammatical errors.
szukalski
Well-known member
I just want to say. I love these posts of yours. I’m very much a beginner learning these things but this stuff is gold. Thanks.
